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A turn-on two-photon fluorescent probe for detecting lysosomal hydroxyl radicals in living cells
摘要： The detection of reactive oxygen species (ROS) in biological systems and its imaging is of great importance. Among them, the hydroxyl radical (?OH) stands out as one of the most reactive, playing an important role in many physiological and pathological processes. Here we report a two-photon (TP) turn-on fluorescent probe with good selectivity and sensitivity towards ?OH. The molecular design of this naphthalene-indoline compound enables it to accurately target lysosomes in its non-fluorescent (“off”) state, where interaction with ?OH gives rise to the fluorescent (“on”) state and allows for the imaging of ?OH generation in living mouse embryonic fibroblast (MEF) cells. The present study provides an approach for improving our understanding of the role of ?OH in biological processes.
关键词： Lysosomes,Two-photon absorption,Biosensors,Fluorescent Probes,Reactive Oxygen Species
更新于2025-09-23 15:23:52
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Influence of Mg doping on the structural, morphological, optical, thermal, and visible-light responsive antibacterial properties of ZnO nanoparticles synthesized via co-precipitation
摘要： Mg-doped zinc oxide (Zn1-xMgxO, where x = 0.000, 0.001, 0.003, 0.005, and 0.010 M) nanoparticles (MgZnO NPs) were synthesized via a co-precipitation method and subjected to various analyses for application as functional additives in food packaging. The MgZnO NPs were successfully formed at approximately 360 °C and showed an increase in the optical band gap with respect to the increase in the concentration of Mg doping. The X-ray diffraction and scanning electron microscopy analyses of MgZnO NPs confirmed the formation of hexagonal wurtzite structure and rod-like morphology. X-ray photoelectron spectra revealed that the Mg (1s) peaks centered at 1303.35 and 1303.38 eV were ascribed to the presence of Mg2+ replacing Zn2+. Transmission electron microscopy images showed rod shapes with the length of 208–650 nm and width of 84–142 nm. Various concentrations of synthesized MgZnO NPs were investigated against a gram-negative (Escherichia coli - DH5α) bacterial strain under light and dark conditions. Among the studied samples, 0.010 M MgZnO NPs of concentration 3 mg/mL showed the best antibacterial activity under the light condition. MgZnO NPs revealed uneven ridges on the outer surface, which promote the diffusion ability of Zn2+ and increased production of reactive oxygen species, and consequently lead to bacterial lysis. Furthermore, this study demonstrates excellent feasibility for the application of MgZnO NPs as fillers with good antibacterial activity, especially in antimicrobial food packaging applications.
关键词： Mg doping,reactive oxygen species,antibacterial activity,nanorod,ZnO
更新于2025-09-23 15:23:52
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Miniaturized electrochemiluminescent biochip prepared on gold nanoparticles-loaded mesoporous silica film for visual detection of hydrogen peroxide released from living cells
摘要： Au nanoparticles (NPs) has been widely used for the detection of intracellular H2O2 to enhance the electron transfer process. But AuNPs are easy to aggregate in the live cells environment. Herein we report a rapid, reliable and low-cost electrochemiluminescent (ECL) biochip integrated by AuNPs-loaded mesoporous silica film (MSF) to detect H2O2 released by macrophage cells. The MSF was employed as a template to load AuNPs within the nanochannels to avoid aggregation. H2O2 could be catalyzed by AuNPs to promote the ECL reaction of luminol molecules in solution. The ECL intensity was significantly enhanced, and the peak potential was negatively shifted by 400 mV due to the excellent electrocatalytic ability of AuNPs. The integrated biochip demonstrated good reproducibility, with a wide linear range of 0.1–200 μM and an LOD of 25.3 nM. The reliability was evaluated by applying for the assessment of antioxidant activity of resveratrol using RAW 264.7 macrophage model. The AuNPs-loaded MSF integrated biochip can be easily adapted to the development of improved devices in biosensing, lab-on-a-chip, and nanofluidic systems.
关键词： Gold nanoparticles,Biochip array,Electrochemiluminescence,Reactive oxygen species,Mesoporous silica
更新于2025-09-23 15:23:52
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Protection mechanisms of periphytic biofilm to photocatalytic nanoparticles (PNPs) exposure
摘要： Researchers are devoting great effort to combine photocatalytic nanoparticles (PNPs) with biological process to create efficient environmental purification technologies (i.e. intimately coupled photobiocatalysis). However, little information is available to illuminate the responses of multispecies microbial aggregates against PNP exposure. Periphytic biofilm, as a model multispecies microbial aggregate, was exposed to three different PNPs (CdS, TiO2, and Fe2O3) under Xenon lamp irradiation. There were no obvious toxic effects of PNP exposure on periphytic biofilm as biomass, chlorophyll content and ATPase activity were not negatively impacted. Enhanced production of extracellular polymetric substances (EPS) is the most important protection mechanism for periphytic biofilm against PNPs exposure. Although PNPs exposure produced extracellular superoxide radicals and caused intracellular reactive oxygen species (ROS) accumulation in periphytic biofilm, the interaction between EPS and PNPs could mitigate production of ROS while superoxide dismutase could alleviate biotic ROS accumulation in periphytic biofilm. The periphytic biofilms changed their community composition in the presence of PNPs by increasing the relative abundance of phototrophic and high nutrient metabolic microorganisms (Families Chlamydomonadaceae, Cyanobacteriacea, Sphingobacteriales and Xanthomonadaceae). This study provides insight into the protection mechanisms of microbial aggregates against simultaneous photogenerated and nanoparticle toxicity from PNPs.
关键词： community composition,EPS,reactive oxygen species,Periphytic biofilm,photocatalyst,nanoparticles
更新于2025-09-23 15:23:52
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A self-illuminating nanoparticle for inflammation imaging and cancer therapy
摘要： Nanoparticles have been extensively used for inflammation imaging and photodynamic therapy of cancer. However, the major translational barriers to most nanoparticle-based imaging and therapy applications are the limited depth of tissue penetration, inevitable requirement of external irradiation, and poor biocompatibility of the nanoparticles. To overcome these critical limitations, we synthesized a sensitive, specific, biodegradable luminescent nanoparticle that is self-assembled from an amphiphilic polymeric conjugate with a luminescent donor (luminol) and a fluorescent acceptor [chlorin e6 (Ce6)] for in vivo luminescence imaging and photodynamic therapy in deep tissues. Mechanistically, reactive oxygen species (ROS) and myeloperoxidase generated in inflammatory sites or the tumor microenvironment trigger bioluminescence resonance energy transfer and the production of singlet oxygen (1O2) from the nanoparticle, enabling in vivo imaging and cancer therapy, respectively. This self-illuminating nanoparticle shows an excellent in vivo imaging capability with suitable tissue penetration and resolution in diverse animal models of inflammation. It is also proven to be a selective, potent, and safe antitumor nanomedicine that specifically kills cancer cells via in situ 1O2 produced in the tumor microenvironment, which contains a high level of ROS.
关键词： photodynamic therapy,cancer therapy,inflammation imaging,reactive oxygen species,myeloperoxidase,bioluminescence resonance energy transfer,nanoparticles
更新于2025-09-23 15:22:29
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Enhancement of cytotoxic effect on human head and neck cancer cells by?combination of photodynamic therapy and sulforaphan
摘要： Photodynamic therapy (PDT) is a method to treat cancers using photosensitizer and light. PDT has been tried for several tumors. However, the clinical applications are limited by the toxicity of photosensitizer and narrow effect. Sulforaphane (SFN) is a material of isothiocyanate group and known to have anticancer effect. We evaluated the cytotoxic effect of PDT combined with SFN on human head and neck cancer cells. We measured the cell viability, extent of apoptosis and necrosis, reactive oxygen species (ROS) generation and caspase activation. Cell viability was decreased significantly by combination treatment. Cellular apoptosis and necrosis were increased in combination treatment compared to SFN or PDT. ROS generation was also higher in combination treatment than single treatment. In combination treatment group, apoptosis and necrosis were decreased by administration of sodium azide (SA) which is scavenger of ROS. Increased caspase activation in combination treatment was also inhibited by SA. Combination of PDT and SFN led to enhanced cytotoxic effect on head and neck cancer cells. Combination treatment promoted the ROS generation, which induced cell death through activation of caspase pathway.
关键词： Sulforaphane,Reactive oxygen species,Head and neck cancer,Photodynamic therapy
更新于2025-09-23 15:22:29
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Heteroleptic Ir(III)N6 Complexes with Long-Lived Triplet Excited States and In Vitro Photobiological Activities
摘要： A series of cationic heteroleptic iridium(III) complexes bearing tris-diimine ligands [Ir(phen)2(R-phen)]3+ (R-phen = phenanthroline (1), 3,8-diphenylphenanthroline (2), 3,8-dipyrenylphenanthroline (3), 3-phenylphenanthroline (4), 3-pyrenylphenanthroline (5), and 3,8-diphenylethynylphenanthroline (6)) were synthesized and characterized. These complexes possessed phen ligand-localized 1π,π* transitions below 300 nm, and charge transfer (1CT) and/or 1π,π* transitions between 300 and 520 nm. In 1, 2, 4, and 6, the low-energy bands were mixed 1CT/1π,π*. However, the increased π-donating ability of the pyrenyl substituent(s) in 3 and 5 split the low-energy bands into a pyrene-based 1π,π* transition at 300-380 nm and an intraligand charge transfer (1ILCT) transition at 380-520 nm. All complexes were emissive at room temperature in CH3CN, but the parentage of the emitting state varied depending on the R substituent(s). Complex 1 exhibited predominantly phen ligand-localized 3π,π* emission mixed with metal-to-ligand charge transfer (3MLCT) character, while the emission of 2, 4, and 6 was predominantly from the excited-state with 3π,π*/3ILCT/3MLCT character. The emission from 3 and 5 was dominated by pyrene-based 3π,π* states mixed with 3ILCT character. The different natures of the lowest triplet excited states were also reflected by the different spectral features and lifetimes of the triplet transient absorption of these complexes. Complexes 3 and 5 had singlet oxygen quantum yields as high as 81 and 72%, respectively. Both gave submicromolar phototoxicities toward cancer cells (SK-MEL-28 human melanoma) and bacteria (S. aureus and S. mutans) with visible light activation (and marginal to no photobiological activity with red light). Their visible-light phototherapeutic indices (PIs) toward SK-MEL-28 cells were 248 for 3 and >435 for 5; PIs were lower in bacteria (≤62) due to their inherent antimicrobial activities. Both complexes were shown to produce substantial amounts of intracellular reactive oxygen species (ROS), which may account for their photobiological activities.
关键词： photophysics,photodynamic therapy,long-lived triplet excited state,antimicrobial,photobiological activities,reactive oxygen species,heteroleptic Ir(III) trisdiimine complexes
更新于2025-09-23 15:22:29
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Enhanced generation of reactive oxygen species and photocatalytic activity by Pt-based metallic nanostructures: the composition matters
摘要： The modification of semiconductor nanostructures with metallic nanocomponents can promote the separation of electron/hole from photoexited semiconductors by forming heterojunctions, thus exhibit enhanced photocatalytic activities and potential applications. In this study, Pt-based NPs, including Pt, PtCu, and PtCuCo are employed as model co-catalysts to comparatively study their capability to enhance the photocatalytic activity of TiO2 nanosheets. It was found that each of Pt, PtCu, and PtCuCo can greatly enhance the photocatalytic activity of TiO2 toward degradation of organic dyes. Using electron spin resonance spectroscopy, we demonstrated that deposition of Pt-based NPs resulted in more production of reactive oxygen species including hydroxyl radicals, superoxide, and singlet oxygen. The enhancing effects of Pt-based NPs on generation of ROS and photocatalytic activity showed same trend: PtCuCo > PtCu > Pt. The mechanism underlying the enhancement differences in Pt-based NPs may be mainly related to electronic structure change of Pt in alloying with Cu and Co. These results are valuable for designing hybrid nanomaterials with high photocatalytic efficiency for applications in water purification and antibacterial products.
关键词： photocatalysis,hybrid nanostructures,reactive oxygen species,PtCuCo,TiO2
更新于2025-09-23 15:22:29
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Oxidation of P700 Ensures Robust Photosynthesis
摘要： In the light, photosynthetic cells can potentially suffer from oxidative damage derived from reactive oxygen species. Nevertheless, a variety of oxygenic photoautotrophs, including cyanobacteria, algae, and plants, manage their photosynthetic systems successfully. In the present article, we review previous research on how these photoautotrophs safely utilize light energy for photosynthesis without photo-oxidative damage to photosystem I (PSI). The reaction center chlorophyll of PSI, P700, is kept in an oxidized state in response to excess light, under high light and low CO2 conditions, to tune the light utilization and dissipate the excess photo-excitation energy in PSI. Oxidation of P700 is co-operatively regulated by a number of molecular mechanisms on both the electron donor and acceptor sides of PSI. The strategies to keep P700 oxidized are diverse among a variety of photoautotrophs, which are evolutionarily optimized for their ecological niche.
关键词： photosynthesis,reactive oxygen species,photoinhibition,P700 oxidation,photosystem I
更新于2025-09-23 15:21:21
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Synergistic interactions of cadmium-free quantum dots embedded in a photosensitised polymer surface: efficient killing of multidrug-resistant strains at low ambient light levels
摘要： Cadmium-free quantum dots (QD) were combined with crystal violet photosensitising dye and incorporated into medical grade polyurethane via a non-covalent dipping process known as ‘swell-encapsulation-shrink’. The antibacterial efficacy of the prepared quantum dot-crystal violet polyurethane substrates (QD + CV PU) was investigated under low power visible light illumination at similar intensities (500 lux) to those present in clinical settings. The antibacterial performance of QD + CV PU was superior to the constituent polymer substrates, eliminating ~99.9% of an environmental P. aeruginosa strain, a clinical P. aeruginosa strain from a cystic fibrosis patient and a clinical E. coli strain. The nature of the reactive oxygen species (ROS) involved in antibacterial activity of the QD + CV PU surface was investigated using ROS inhibitors and time-resolved optical spectroscopy. The photo-physical interaction of the green-emitting QDs with CV lead to a combination of Type I and II electron transfer and energy transfer processes, with the highly potent ROS singlet oxygen playing a dominant role. This study is the first to demonstrate highly efficient synergistic killing of clinical and environmental strains of intrinsically resistant and multi-drug resistant Gram-negative bacteria using light-activated surfaces containing biocompatible cadmium-free QDs and crystal violet dye at ambient light levels.
关键词： photodynamic therapy,antibacterial,reactive oxygen species,surfaces,quantum dots
更新于2025-09-23 15:21:01